/Engine/Plugins/Online/OnlineServices/Source/OnlineServicesCommon/Public/Online/LobbiesCommon.h
Change the attributes applied to a lobby member. Lobby members may only change their own attributes. Attributes are validated against the lobby schema before an update can succeed.
virtual [TOnlineAsyncOpHandle](API\Plugins\OnlineServicesInterface\Online\TOnlineAsyncOpHandle)< [FModifyLobbyMemberAttributes](API\Plugins\OnlineServicesInterface\Online\FModifyLobbyMemberAttributes) > ModifyLobbyMemberAttributes ( [FModifyLobbyMemberAttributes::Params](API\Plugins\OnlineServicesInterface\Online\FModifyLobbyMemberAttributes\Params) && Params )